All bar or restaurant owners have a problem monitoring the amount of usable beer or wine remaining in the system, as beverage kegs are sealed pressure vessels that mask their content. Current inaccurate options for determining keg content typically include weighing the keg and its contents, lifting the keg to estimate the beer or wine volume, and zeroing a flow meter when a keg is full and subtracting out measured flow to estimate a remaining volume.
A related problem within the draft beer industry is called “blowing a keg.” Carbon dioxide gas enters the keg through a hose distribution system coupled to a valve assembly atop the keg's neck, creating pressure in the keg and pushing the beverage up the dip tube. When there is a sufficient liquid in a keg, the opening in the bottom of the dip tube is below the surface of the liquid, and only liquid enters the dip tube. However, when the liquid in the keg drops low enough, CO2 enters the dip tube and the hose connecting the keg to the tap dispenser. The tap begins to dispense foam, and CO2 gas pockets blow portions of liquid at a high rate out of the tap. Bartenders refer to this as a “beer shower.” Now soaked, the bartender must go replace the empty keg. Once the bartender gets back, the tap must be opened to release all the gas that has entered the hose. Additional CO2, foam, and foamy liquid must be dispensed until a good, solid stream of liquid is seen. The mess and wasted beer are problems.
Owners make many assumptions, including delivery of a full keg, a correct number of ounces in each mug served, that the bartender collects money for every ounce poured, and that “beer showers” are an unavoidable aspect of the business. These various losses may easily cost an owner about fifteen percent of profits. Yet this profit loss is presently commercially undetectable.
There is need in the art for accurate, real-time measurements and warnings to help uncover theft and other losses, and to help bartenders manage liquid inventory within a keg while avoiding the unpleasant problems associated with blowing a keg.